Professor White has written some short stories, but he is________known for his plays.
You________ the work better, but you didn’t put more efforts to it.
The professor you referred to in the letter______ us students three lectures by next Monday.
—What do you think has caused his heart attack? —It is ______.
—Do you have any idea why the engineer resigned?—No. In fact, everyone is ____about it.
It’s required that the students______ mobile phones in their school, so seldom ______ them using one.